Fire access door unit



Jan. 17, 1967- J. H. GREEN FIRE ACCESS DOOR UNIT Filed March 26. 1964 Inventor m m a? V f Tm d United States Patent 3,298,397 I FIRE ACCESS DOOR UNIT James Hugh Green, Greenford, Middlesex, England, as-

signor to James Green Developments Limited, London, England, a British company Filed Mar. 26, 1964, Ser. No. 354,872 7 Claims. (Cl. 138-92) This invention relates to a fire access door unit and par ticularly to a fire access door unit for use in a ventilating or similar ducting system.

A very considerable firehazard arises out of the use of ducted ventilation, particularly when the inlet to the fan operated ducting is in the vicinity of machines orother apparatus where small conflagrations, which might otherwise be quite harmless may arise.

Hitherto it has not been possible to deal with fires in ventilating systems in a satisfactorily safe manner, as the fireman has not been able readily to gain access to the ducting for directing water thereinto. In most cases access to the desired part of the ducting can only be gained by breaking a hole through the ducting Wall with a firemans axe or similar implement. However, once the duct has been punctured, the intense heat of the flames issuing through the hole, makes it very difficult for the firemen to approach the relevant part of the duct for the purpose of enlarging the hole sufiiciently to enable water to be directed thereinto. Even if the fire is not in, or does not extend into, the duct, it would often be of great advantage if easy access to a duct could be provided to enable water to be poured thereinto to prevent air flow fanning the fire and/or to conduct the Water into the space in which the fire is burning. It is therefore an object of this invention to provide an access door unit for ventilation or similar ducting, such access door enabling the directing of water into the ducting readily and safely. I

According to this invention, the access door unit for ventilation or similar ducting comprises a tubular body closed at one end by a readily frangible panel and having its other end closed by a pivoted door operable by pressure acting over the face nearer to the frangible panel, but not by pressure acting over the face remote from the frangible panel.

When the unit according to this invention is installed in a ducting system, a hole is made in the ducting and the unit fitted in a sealed manner over this hole with the frangible panel end of the tube outermost. It will be appreciated that, in the event of a fireman requiring access to the ducting, he has merely to break the frangible panel. The pivoted door prevents flames issuing from the ducting, but water, e.g. from a hose, can be directed into the opening made by breaking the panel and the pressure of the water will pivot the door open to admit the water. Thus the door acts as a non-return flap valve and the ducting is kept closed until the water is directed into the ducting.

The unit of this invention may be fitted to existing ducting or may be incorporated in new ducting either as a separate component affixedthereto or as an integral part thereof.

Preferably the frangible panel is secured to the tubular body by any suitable readily releasable means, such as wing nuts, to enable the unit to be used under normal circumstances as an inspection door or to enable a fireman to open the duct readily without breaking the panel if it is safer for him to do so.

Advantageously, the frangible panel is made of asbestos and also advantageously the door is made of perforated material, such as wire gauze and is spaced from the frangible panel by a distance greater than the normal length of penetration of flames through such perforated material. Such a door would, when the frangible panel ice is broken or removed, permit smoke to issue from the duct. In one form of unit according to the invention the tubular body, which is conveniently of square cross-section, is adapted to be secured to the ducting by means of a flange securable to the ducting wall by any suitable means. The flange may be positioned at any point along the length of the body, or even on extensions thereof beyond the panel or door. If it is important that the unit should not interrupt the flow pattern of fluid passing through the duct, then the flange would be located at the door-provided end of the body. On the other hand, if it is important that the unit should fit flush onto the ducting, the flange would be located at the panel-provided end of the body.

In order that the invention may more readily be understood one embodiment thereof will now be described in detail by way of example, reference being made to the accompanying drawing in which:

FIGURE 1 is a sectional side elevation of the embodiment shown secured to a length of ducting; and

FIGURE 2 is a perspective view of the unit of FIG- URE 1;

Referring now to the drawing, the unit comprises a square cross-sectioned tube 10 of about 6 inches side length, constructed of sheet metal and having a small terminal portion 11 of one end of each side bent radially inwardly. To each terminal portion 11 is welded a threaded stud 12 which extends axially outwardly of the unit. At the other end of the tube, a hinge pin 13, located along the top of the tube, carries a door 14 of wire gauze which can swing about the pin 13 outwardly of the unit from the position shown in which it covers the end of the tube.

A second sheet metal tube 15, also of square cross-section, is fitted with its radially outer face against the radially inner face of the first tube 10. The axially outer end is positioned flush against the axially inner face of the inturned terminal portions 11, while the second tube is of such a length that the other, or inner end is spaced just axially outwardly of the inner end of the first tube. Thus the second tube acts as an abutment for the door 14, preventing the latter from opening into the tube 10.

Welded to the outer end of the first tube is a radially outwardly extending annular attachment flange 16 which provides means for securing the unit over a hole in ducting 17 to which the unit is to be fitted.

The unit is completed by a frangible asbestos panel 18, which is secured over the outer end of the tube by means of the screwed studs 12 passing through holes in the panel and bywing nuts screwed onto the studs.

With the unit fixed by means of the flange 16, into the wall of a ventilation duct 17, in the event of a fire in the duct a fireman simply has to break the asbestos panel 18 and direct water from a fire hose through the thus made aperture.

The presence of the hinged door 14 ensures that breaking of the panel does not permit flames to issue outwardly from the ducting as would happen if a hole were made in the wall of the ducting. Since the panel 18 can readily be removed simply by undoing the wing nuts the ducting can be inspected at any time. In particular, if fire is suspected the panel 18 can be removed and smoke issuing through the perforations of the gauze door 14 would indicate the presence of a fire.

Many modifications of the unit are contemplated within the scope of the invention. For example, in order not to interrupt the fluid flow pattern through the ducting the attachment flange 17 may be provided at the end of the tube in which the door 14 is fitted. As desired, the panel 18 may be made of any suitable frangible material, for example, heat proof glass and may be painted with luminous paint so as to be readily visible. If the weight of the door 14 is not sufficient to ensure that it remains closed except when forcibly pivoted, as by the pressure of a jet of water from a fire hose the door may be biassed by a weight, spring or other suitable means.

I claim:

1. A fire access door unit for ventilation ducting such unit comprising a tubular body defining an interior to said unit; first and second ends to said body; a flange affixed to the first end of said body for securing said panel into a duct; a readily frangible asbestos panel releasably securable to said first end of said body and effective to close said first end; a pivotable wire gauze door; an upper edge to said door; pivot means at said upper edge elfective to pivot said door to said body, said door being openable under the action of excess pressure in the interior of said unit and abutment means preventing said door opening under the action of pressure exterior of said unit.

2. A fire access door as specified in claim 1 wherein said door is spaced from said panel, by said tubular body, by a distance greater than the length of flame penetration through said wire gauze door.

3. In a ventilation ducting system, a fire access door unit extending to the interior of said ducting; a tubular body of square cross section defining the interior of said unit; a flange afiixed to the first end of said body and secured to said ducting; a readily frangible asbestos panel releasably securable to said first end of said body and effective to close said first end; a pivotable wire gauze door; an upper edge to said door; pivot means at said upper edge eflective to pivot said door to said body, said door being openable under the action of excess pressure in the interior of said unit and abutment means preventing said door opening under the action of pressure exterior of said unit.

4. A fire access door unit for ducting, such unit comprising a tubular body defining an interior to said unit; first and second ends to said body; a readily frangible panel; releasable means to secure said readily frangible panel at said first end of said tubular body effective to close said first end, and to enable said panel to be removed from said unit without breaking said panel, a pivotable door formed of perforated material closing said second end of said body and openable by pressure in the interior of said unit and means preventing said panel from opening under pressure exterior of said unit.

5. A fire access door unit as specified in claim 4, said door including an upper edge; pivot means secured to said upper edge to pivot said door to said body, whereby said door is normally closed under its own weight.

6. A fire access door unit as specified in claim 4, wherein the tubular body is provided with a flange to enable said unit to be secured to a ducting wall.

7. A fire access unit as specified in claim 6, wherein said flange is provided at said first end of said tubular body.

References Cited by the Examiner UNITED STATES PATENTS 833,694 10/1906 Parker. 2,034,231 3/1936 Fox 98l 14 X 2,417,374 3/ 1947 Morton.

LAVERNE D. GEIGER, Primary Examiner.

T. MOORHEAD, Assistant Examiner. 

4. A FIRE ACCESS DOOR UNIT FOR DUCTING, SCH UNIT COMPRISING A TUBULAR BODY DEFINING AN INTERIOR TO SAID UNIT; FIRST AND SECOND ENDS TO SAID BODY; A READILY FRANGIBLE PANEL; RELEASABLE MEANS TO SECURE SAID READILY FRANGIBLE PANEL AT SAID FIRST END OF SAID TUBULAR BODY EFFECTIVE TO CLOSE SAID FIRST END, AND TO ENABLE SAIDPANEL TO BE REMOVED FROM SID UNIT WITHOUT BREAKIN SAID PANEL, A PIVOTABLE DOOR FORMED OF PERFORATED MATERIAL CLOSING SAID SECOND END OF SAID BODY AND OPENABLE BY PRESSURE IN THE INTERIOR OF SAID UNIT AND MEANS PREVENTING SAID PANEL FROM OPENING UNDER PRESSURE EXTERIOR O SAID UNIT. 